Technical Field
Embodiments of the invention relate generally to magnetic resonance imaging and, more specifically, to a system and method to mitigate artifacts in 3D radial images.
Discussion of Art
Magnetic Resonance Imaging (MRI) is a widely accepted and commercially available technique for obtaining digitized visual images representing the internal structure of objects having substantial populations of atomic nuclei that are susceptible to nuclear magnetic resonance (NMR). In MRI, imposing a strong main magnetic field (B0) on the nuclei polarizes nuclei in the object to be imaged. The nuclei are excited by a radio frequency (RF) signal at characteristic NMR (Larmor) frequencies. By spatially distributing localized magnetic fields surrounding the object and analyzing the resulting RF responses from the nuclei as the excited protons relax back to their lower energy normal state, a map or image of these nuclei responses as a function of their spatial location is generated and displayed. An image of the nuclei responses provides a non-invasive view of an object's internal structure.
Since the discovery of NMR imaging, a variety of different imaging schemes have been developed to improve image quality or to fit special requirements. Relatively recently, a zero echo time (ZTE) imaging technique was discovered that substantially decreased the image acquisition echo time. Zero echo time can be obtained in MRI by performing RF excitation as well as acquisition in the presence of a constant gradient applied for purely frequency-encoded, radial center-out k-space encoding. With existing 3D radial imaging sequences, however, image artifacts, such as subtle streaking in some central slices when acquiring head images with an axial orientation, have been observed.
What is needed, therefore, is a system and method that improves overall imaging performance and, in particular, eliminates artifacts during 3D radial head imaging when acquiring with an axial orientation.